1. Field of the Invention
The present invention relates to devices for pipe inspecting. More particularly, the present invention relates to inspection devices, carrying inspection probes (sometimes called "rabbits"), that have sufficient flexibility to negotiate bends in piping systems.
2. Discussion of Background
Cleaning, inspecting and testing are widely known in the construction and maintenance of piping systems. Devices carrying testing and inspection probes, or "rabbits", are used to move these probes through piping systems so that they can survey surfaces of piping and look for damaged or flawed structural features. Typically, such inspection devices comprise a testing probe, such as an eddy current probe, contained within a rabbit support structure that travels through the piping system being inspected.
Several U.S. Pat. Nos. disclose devices carrying eddy current testing probes, including 5,023,549 issued to Dau et al, 4,952,875 issued to Adams et al, 3,916,302 issued to Madewell and 4,413,231, issued to Amedro et al.
To be effective, testing and inspection devices must be dimensioned to pass through various sized pipes and designed to negotiate piping bends easily. Therefore, the relative size and flexibility of a particular inspection device is often crucial.
There have been a number of attempts to design flexible rabbits for pipe inspection. Dau et al (5,023,549) feature an expandable elastic membrane for supporting an eddy current sensor to be used in nuclear plant piping. The flexible membrane is made of rubber, plastic or a similar material.
Adams et al (4,952,875) disclose an eddy current testing device for U-shaped tubes in a heat exchanger. The device includes a plurality of elastic hoses separated by coils, a local recognition unit and an elastic insertion tip at the front end. Similarly, Amedro et al (4,413,231) have an insertion tip, a measuring head, a probe body and connecting members.
Many pipe inspection devices are modular in configuration in order to enhance their flexibility. For instance, deBuda et al (4,372,161) and Madoian et al (4,195,529) both disclose pneumatically operated, modular units that move through piping. DeBuda et al ('161) feature an elongate cylindrical tube of flexible resilient material, partitioned by longitudinally spaced plugs which are hermetically sealed to the wall of the tube to form a series of chambers. Madoian et al ('529) use chambers surrounded by elastic sleeves and interconnected by a flexible bellows to move probes of a flaw detection system through piping.
Another patent, U.S. Pat. No. 5,174,164, issued to Wilheim, discloses a flexible cable for carrying an inspection probe through tubing. The cable comprises a core with a plurality of adjacent, interconnecting beads surrounding and disposed along the exterior. Each pair of adjacent beads defines a ball and socket joint for allowing the cable to flex as it is moved in the tubing.
Although many devices for inspecting piping are currently known and available, there exists a need for an pipe inspection device made to pass easily through piping and having the requisite flexibility to negotiate severe bends in the piping system being inspected.